Patent Document 1 describes an example of conventional cutting inserts. Specifically, the cutting insert in Patent Document 1 is a cutting insert comprising two end surfaces whose contour shapes are each substantially polygonal and a peripheral side surface extending between the these end surfaces, wherein cutting edges are formed in an intersecting edge between each of the end surfaces and the peripheral side surface. The cutting edges comprise corner cutting edges, main cutting edges and wiper edges. However, Patent Document 1 does not particularly include any description concerning an intersection angle between the two end surfaces and the peripheral side surface. With reference to the figures of the same document, as viewed from a direction facing the side surface part of the main cutting edge, the boundary between the side surface of a wiper edge and the side surface of the main cutting edge extends in a direction perpendicular to the two end surfaces, which suggests that such cutting insert is of a negative type.